This invention relates to curable compounds that have a cycloaliphatic epoxy moiety and a styrenic, cinnamyl, or maleimide moiety.
Radical-curable compositions are used in adhesive compositions, for example, in the fabrication and assembly of semiconductor packages and microelectronic devices. There are a number of electron donor/electron acceptor adhesive systems that are used in the industry, but not all these give as full performance as is needed for all uses. There are also adhesive systems that contain both radical-curable moieties and epoxy functionality. The compounds disclosed in this specification add to the spectrum of performance materials for use within the semiconductor fabrication industry.
This invention relates to compounds that have a cycloaliphatic epoxy moiety and an electron acceptor moiety or an electron donor moiety. The preferred electron acceptor is a maleimide moiety. The preferred electron donor is a double bond connected to an aromatic ring and conjugated with the unsaturation in the ring. Preferred electron donor moieties are styrenic or cinnamyl moieties. In another embodiment, this invention is a curable composition, such as an adhesive, coating, or encapsulant composition, containing such compounds.
The inventive compounds can be represented by the formulas (in which the bond represented as a wavy line indicates a cis or trans isomer or a racemic mixture of the compound): 
represents a cycloaliphatic epoxy moiety, in which an epoxy group is fused to a cyclic, bicycle or tricyclic ring structure, which structure may contain one or more heteroatoms (N, O, or S); preferably, the cycloaliphatic epoxy moiety is chosen from substituted and unsubstituted five and six membered cyclic rings; substituted and unsubstituted six, seven and eight member bicyclic rings; substituted and unsubstituted nine, ten and eleven member tricyclic rings, in which the substituents on the rings can be any organic moiety, and preferably are lower alkyl;
R, Rxe2x80x2, and Rxe2x80x3 are independently hydrogen, an alkyl group having 1 to 12 carbon atoms and preferably H or 1 to 4 carbon atoms, or an aromatic or heteroaromatic ring or fused ring having 3 to 10 carbon atoms within the ring structure, in which the heteroatoms are N, O, or S;
G is xe2x80x94OR, xe2x80x94SR, or xe2x80x94N(R)(Rxe2x80x2) in which R and Rxe2x80x2 are as described above; or G is an alkyl group having 1 to 12 carbon atoms; or G is an aromatic or heteroaromatic ring or fused ring having 3 to 10 carbon atoms within the ring structure, in which the heteroatoms may be N, O, or S;
Z and Zxe2x80x2 are any monomeric, oligomeric or polymeric organic moiety (for example, alkyl, cycloalkyl, aryl alkyl alkenyl, cycloalkenyl, aryl alkenyl, or aromatic, and for example poly(butadiene), polyether, polyester, polyurethane, polyacrylic, polystyrene, polycarbonate, polysulfone); and
X is a direct bond or a functional group selected from the groups consisting of: 
provided that X cannot be oxygen when the cyclic epoxy is epoxy cyclohexane and the other functionality is a styrenic moiety.
Exemplary structures with the cyclic epoxy moieties depicted for such compounds, in which E represents the styrenic, cinnamyl, or maleimide moiety; X, Z, and Zxe2x80x2 are as above and R and Rxe2x80x2 are hydrogen or lower alkyl, and q and v independently are 0 or 1, include: 
In another embodiment, this invention is a curable composition, such as an adhesive, coating, or encapsulant, containing the compound with both cycloaliphatic epoxy and styrenic, cinnamyl, or maleimide functionality. The composition can be a paste, prepared by blending or milling, or can be a film, prepared by standard film making techniques known to those skilled in the art The curable composition will include optionally a curing agent, and optionally a filler.
These compounds can be the main component in the curable composition or can be added as an adhesion promoter to one or more other curable resins. When used as an adhesion promoter, the amount used in the curable composition will be an effective amount to promote adhesion and, in general, an effective amount will range from 0.005 to 20.0 percent by weight of the formulation.
Examples of other curable resins for use as the main component in the curable compositions include epoxies, vinyl ethers, thiolenes, compounds derived from cinnamyl and styrenic starting compounds, fumarates, maleates, acrylates, and maleimides.
Suitable curing agents are thermal initiators and photoinitiators present in an effective amount to cure the composition. In general, those amounts will range from 0.1% to 30%, preferably 1% to 20%, by weight of the total organic material (that is, excluding any inorganic fillers) in the composition. Preferred thermal initiators include peroxides, such as butyl peroctoates and dicumyl peroxide, and azo compounds, such as 2,2xe2x80x2-azobis(2-methyl-propanenitrile) and 2,2xe2x80x2-azobis(2-methyl-butanenitrile). A preferred series of photoinitiators are those sold under the trademark Irgacure or Rhodorsil 2074 by Ciba Specialty Chemicals. In some formulations, both thermal initiation and photoinitiation may be desirable: the curing process can be started either by irradiation, followed by heat, or can be started by heat, followed by irradiation.
In general, the curable compositions will cure within a temperature range of 60xc2x0 C. to 250xc2x0 C., and curing will be effected within a range of three seconds to three hours. The actual cure profile will vary with the components and can be determined without undue experimentation by the practitioner.
The curable compositions may also comprise nonconductive or thermally or electrically conductive fillers. Suitable conductive fillers are carbon black, graphite, gold, silver, copper, platinum, palladium, nickel, aluminum, silicon carbide, boron nitride, diamond, and alumina. Suitable nonconductive fillers are particles of vermiculite, mica, wollastonite, calcium carbonate, titania, sand, glass, fused silica, fumed silica, barium sulfate, and halogenated ethylene polymers, such as tetrafluoroethylene, triflouroethylene, vinylidene fluoride, vinyl fluoride, vinylidene chloride, and vinyl chloride. If present, fillers generally will be in amounts of 20% to 90% by weight of the formulation.
In another embodiment, this invention is a curable composition comprising the compound having a cycloaliphatic epoxy moiety and a styrenic, cinnamyl, or maleimide moiety, and an aliphatic or aromatic epoxy resin. In a preferred embodiment, the epoxy resin has the structure 